diff --git a/ext/gio/gstgiosink.h b/ext/gio/gstgiosink.h
index 6d4de8d6f2..474f7cfdd2 100644
--- a/ext/gio/gstgiosink.h
+++ b/ext/gio/gstgiosink.h
@@ -42,10 +42,16 @@ G_BEGIN_DECLS
 typedef struct _GstGioSink      GstGioSink;
 typedef struct _GstGioSinkClass GstGioSinkClass;
 
+/**
+ * GstGioSink:
+ *
+ * Opaque data structure.
+ */
 struct _GstGioSink
 {
   GstBaseSink sink;
 
+  /*< private >*/
   GCancellable *cancel;
   GFile *file;
   gchar *location;
diff --git a/ext/gio/gstgiosrc.h b/ext/gio/gstgiosrc.h
index d8b64af432..dfed9cde0f 100644
--- a/ext/gio/gstgiosrc.h
+++ b/ext/gio/gstgiosrc.h
@@ -42,10 +42,16 @@ G_BEGIN_DECLS
 typedef struct _GstGioSrc      GstGioSrc;
 typedef struct _GstGioSrcClass GstGioSrcClass;
 
+/**
+ * GstGioSrc:
+ *
+ * Opaque data structure.
+ */
 struct _GstGioSrc
 {
   GstBaseSrc src;
-
+  
+  /*< private >*/
   GCancellable *cancel;
   GFile *file;
   gchar *location;